I just installed a Garnet SeeLevel2 mod 711T in my MCI. I have plastic 100 gal fresh and 100 gal combination black/gray tanks with 1/4" walls. The system uses a 16"x3" self adhesive circuit board strip. You can stack them for greater length or cut them off in 1" increments to a minimum of 6". It is hard wired to an electronic monitor panel. It was very easy to install and works great. And it wasn't made in China. It was made in Canada. By the way, this is not a paid ad. It was regularly $355. on sale for $211. So far I'm tickled to death with it.

Do the sensors stick to the outside of the tank or the inside? I bought a monitoring system which uses electrical contacts inside the tank, but people on here have since said that kind of system quickly stops working when used on black or grey tanks (I haven't installed mine yet, so cannot comment).

A system with sensors which read through the wall of a plastic tank seems a better approach - anyone know of a source to buy such sensors separately, for connecting to an existing monitor?

Extra Sensor board for all Seelevel II Model 709 systems. Sensor boards are 12" tall and can be cut down and combined to fit any size tank.

FeaturesEach sender panel is a flexible self-adhesive printed circuit board which is mounted to the side of the holding tank. The sender scans the water level through the tank wall using patented digital techniques programmed into the sender microprocessor. When a sender transmits the water level information to the display, it sends a digital code that has built-in error detection, making it impossible for the display to read an incorrect level, even if the wiring is bad.

So, I'd like to find a 'non-proprietary' sensor that works in the same way - ie., one which gives a simple 'on / off' type output depending on whether it senses water or not, which I could then use to replace my in-tank sensors

Jeremy, Many years ago I had a tank sensor system that used outside tape. As I remember it , it required to strips of tape per tank a certain distance apart. It worked fine. The tanks on this bus though came with the through the wall type sensors, so I bought a cheap system to hook them up. The fresh water works fine, but the black/grey tank never reads below half full. It's not like I like it, but still usable since the upper sensors in that tank work fine. The company that makes the system I have also makes an outside tape system. Unfortunately, the control panel is different so I have not been real motivated to buy it. However, if you are starting from scratch there is no reason not to just go with the tape one.

I tried to do this on the cheap with a hand held stud finder with mixed results! Sometimes it works and sometimes it doesn't. Maybe a better quality stud finder would be better, I may try that next. If it doesn't work I can always use it as a stud finder!!

I thought about the in tank sensors but decided it is not a good system since I'm mostly concerned about the waste tank but the sides of the waste tank are stained.

I have the most reliable, never to break or give a false reading gauge for my fresh, gray and black water tank. I have a halogen puck light above each tank and just turn on the light to see the level in the tank. The key is to have the black water tank made with normal white plastic-not have the carbon black injected into the plastic. Good Luck, TomC

I find trying to see the level through the tank pretty difficult unless the light is right. Definitely not my first choice in the desert sun. Shining a flashlight down the toilet works though when I want to verify the monitor.

Like Tom, I like KISS, so my gray tank has a 12-volt Malibu garden light with a 20W MR16 lamp that shines against the far side of it. The poo tank is easily visible, and the two fresh tanks have a sight glass, again about as simple as it gets. The only think electronic on my bus is the !"#$%& DDEC II, and even thatīs too much electronics for my liking.

Greetings from Cordoba MX where Iīm enjoying a well-deserved break from SoCal,John

I have identical tanks. 100 fresh, 100 gray/black.They are the opaque plastic, so I can see in them.

I have three tank monitor systems. No matter how much I clean the probes, or replace them with new, they stop working after a while. The outside stick on foil works the best, but even it will stop after a while. All a waste of money in my opinion.

I now have a piece of plexiglass on each sidewall of the tank areas. There are lights installed in the bay above the tanks. I can see both levels. They correlate, if the fresh is down a fourth, the waste is up a fourth.

I can also see down the toilet into the waste. That level tells me the fresh.

I've used those methods for 17 years. They never fail. I gave up and stopped the monitor fixing several years ago.

I suggest that you sidestep the electrical sensor issue, and use a Magnehelic pressure gage, They are available calibrated in inches of water, are absolutly accurate, and ebay is full of them. A tube into the bottom of the tank, and a slow pressure source -- a little 12 volt tire inflator will do -- with the gage 'teed' into the line, and you have it.